<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .header {
        display: flex;
        height: 40px;
        border: 1px solid red;
      }
      .logo {
        flex-grow: 1;
      }

      input {
        flex-grow: 2;
      }

      button {
        flex-grow: 1;
      }
      /* button,
      input {
        height: 30px;
      } */
    </style>
  </head>
  <body>
    <div class="header">
      <div class="logo">logo</div>
      <input type="text" placeholder="请输入关键字搜索" />
      <button>搜索</button>
    </div>
  </body>
</html>
